From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Richard B. Johnson" Subject: Re: tcp vulnerability? haven't seen anything on it here... Date: Thu, 22 Apr 2004 07:35:54 -0400 (EDT) Sender: netdev-bounce@oss.sgi.com Message-ID: References: Reply-To: root@chaos.analogic.com Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=X-UNKNOWN Content-Transfer-Encoding: quoted-printable Cc: "David S. Miller" , linux-kernel@vger.kernel.org, netdev@oss.sgi.com, cfriesen@nortelnetworks.com, =?ISO-8859-1?Q?J=F6rn?= Engel Return-path: To: Giuliano Pochini In-Reply-To: Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org On Thu, 22 Apr 2004, Giuliano Pochini wrote: > > On 21-Apr-2004 David S. Miller wrote: > > On Wed, 21 Apr 2004 19:03:40 +0200 > > J=F6rn Engel wrote: > > > >> Heise.de made it appear, as if the only news was that with tcp > >> windows, the propability of guessing the right sequence number is no= t > >> 1:2^32 but something smaller. They said that 64k packets would be > >> enough, so guess what the window will be. > > > > Yes, that is their major discovery. You need to guess the ports > > and source/destination addresses as well, which is why I don't > > consider this such a serious issue personally. > > Yes, but it is possible, expecially for long sessions. Also, > data injections is also possible with the same method, because > the receiver accepts everything inside the window, which is > usually 64k. Out of curiosity: in case Linux receives two > packets relative to the same portion of the stream, does it > check if the overlapping data is the same ? It would add extra > security about data injection in case the data has not been > sent to userspace yet. > > Has anybody checked to see what Linux does if it receives a RST to the broadcast address? It would be a shame if all connections were dropped! Cheers, Dick Johnson Penguin : Linux version 2.4.26 on an i686 machine (5557.45 BogoMips). Note 96.31% of all statistics are fiction.